Not applicable.
This invention relates to an artificial airway device designed to facilitate lung ventilation and the insertion of endo-tracheal tubes or related medical instruments into the laryngeal opening of an unconscious patient, and more specifically, to a laryngeal mask device designed to be placed within the oropharynx region over the laryngeal opening, and secured by means of air inflation, thereby sealing the circumference of the laryngeal opening against the aspiration of regurgitated gastric contents and providing a direct pathway from a point exterior to the oral cavity to the retainer for laryngeal opening.
In general, laryngeal masks allowing for both rapid lung ventilation and the insertion of medical instruments and tubes into the laryngeal openings of patients have been described in patents such as Brain, U.S. Pat. No. 4,509,514. Consisting of two essential parts, a breathing tube and an inflatable mask, these devices are inserted blindly into a patient""s throat, and when properly positioned, terminate at the laryngeal opening. A seal is then formed around the circumference of the laryngeal opening by the inflation of a ring-like structure located on the front of the mask. Inflation of the ring exerts pressure against both the front and rear portions of the oropharynx, securing the device in place such that the laryngeal opening is positioned within a recessed cavity in the mask face. Extending from a point external to the oral cavity, the flexible breathing tube terminates within the recessed cavity, aligned axially with the laryngeal opening. The positioning of the flexible breathing tube allows the passage of small diameter endo-tracheal tubes or related medical instruments into the laryngeal opening, in addition to allowing for lung ventilation.
Current laryngeal masks have several drawbacks in the areas of placement, lung ventilation, and endo-tracheal intubation. For example, during insertion and positioning, the flexible nature of the deflated ring structure and surrounding mask may allow the distal end of the mask to bend back on itself, preventing proper inflation and the formation of a tight seal. Also, once successfully installed, the current mask designs may fail to exert sufficient pressure against the larynx necessary to maintain proper positioning during intubation and ventilation. This is due to the variations in anatomy of the oropharynx region, the muscular tension against which the mask is exerting pressure, and the curvature of the device itself.
During lung ventilation, it is possible for the tip of the epiglottis to become lodged in the distal lumen of the flexible breathing tube, preventing the passage of air or endo-tracheal tubes. This problem is often overcome by the placement of a series of band structures at the entrance to the distal lumen, preventing the epiglottis from entering the breathing tube. However, these band structures severely restrict the size of endo-tracheal tubes and related medical devices which may be passed through the flexible breathing tube. Furthermore, after the insertion of an endo-tracheal tube or related medical device, it often becomes difficult to remove the laryngeal mask from the patient""s oropharynx without dislodging or accidentally extracting the endo-tracheal tube or medical device along with the laryngeal mask.
The removable laryngeal mask of the present invention overcomes these problems and is distinguished from the prior art by providing generally the same function as described above yet allowing a more secure and certain insertion, allowing the unrestricted passage of large diameter endo-tracheal tubes directly to the laryngeal opening, and providing alternate airways to prevent blockage of the flexible breathing tube during patient ventilation.
Among the several objects and advantages of the present invention include:
The provision of a new and improved laryngeal mask for the facilitation of lung ventilation and the insertion of endo-tracheal tubes and related medical instruments into the laryngeal opening;
The provision of the aforementioned laryngeal mask which includes a flexible breathing tube portion and an inflatable mask portion, each gently curved along a single arcuate curve for ease of insertion and positioning;
The provision of the aforementioned laryngeal mask which includes an air-tight seal securing the inflatable mask to the distal end of the flexible breathing tube, said mask contoured to the anatomy of the oropharynx region of the throat;
The provision of the aforementioned laryngeal mask which includes a stiff support structure for the inflatable mask formed by the distal end of the breathing tube, and a contoured rear surface on the inflatable mask, both aiding in the insertion and positioning of the device within the oropharynx;
The provision of the aforementioned laryngeal mask which includes a perforated extension of the flexible breathing tube within the inflatable mask portion so as to provide alternate airways in the event the distal lumen is blocked;
The provision of the aforementioned laryngeal mask which includes a flexible breathing tube having an elliptical cross-section, composed of a deformable, low friction material so as to permit the passage of large diameter endo-tracheal tubes and related medical instruments;
The provision of the aforementioned laryngeal mask which includes an endo-tracheal tube retainer for use in conjunction with the laryngeal mask and endo-tracheal tubes, the endo-tracheal tube retainer facilitating the removal of the laryngeal mask from a patient""s oropharynx without the accidental displacement of any inserted endo-tracheal tubes; and
The provision of the aforementioned laryngeal mask which includes an endo-tracheal tube retainer which may also be placed in a patient""s oropharynx and serve as an intubating stylet.
Briefly stated, the removable laryngeal mask of the present invention is primarily intended to facilitate lung ventilation and the insertion of endo-tracheal tubes or related medical instruments into a patient""s trachea as needed during general anesthesia, intensive care, or critical patient care. The removable laryngeal mask comprises a flexible ventilation tube and an inflatable positioning shield conforming to the anatomy of the oropharynx region surrounding the laryngeal opening, and securely affixed to the distal end of the ventilation tube. A separate endo-tracheal tube retainer facilitates removal of the laryngeal mask from the patient""s oropharynx without dislodging any endo-tracheal tubes or related medical instruments passing through the laryngeal mask into the patient""s trachea.
The flexible ventilation tube of the laryngeal mask is gently curved along an arc approximating the curvature of the passage from a patient""s oral cavity to the laryngeal region. The ventilation tube is of sufficient length that the tube terminates exterior to the oral cavity after proper insertion and positioning of the laryngeal mask, thereby allowing endo-tracheal tubes and related medical devices to be easily inserted or attached. The ventilation tube is composed of a low-friction elastic plastic polymer, and has an elliptical cross section closely conforming to the actual cross section of the human throat. Large diameter endo-tracheal tubes and related medical instruments may pass freely through the flexible ventilation tube due to the low friction nature of the plastic polymer and the ability of the tube to deform to accommodate the larger diameter medical instruments. Passing through the rear portion of the inflatable positioning shield, the flexible ventilation tube terminates at an angle to the length of the tube, creating an elongated distal lumen open to the front recess of the inflatable positioning shield. The elongated distal portion of the ventilation tube forming the distal lumen serves the additional function of providing a semi-rigid substructure onto which the inflatable positioning shield is secured.
In addition to the elongated elliptical distal lumen, the peripheral surface of the flexible ventilation tube distal end contains numerous auxiliary ventilation lumen open to the front recess of the inflatable positioning shield. These auxiliary ventilation lumens function to provide alternate air passageways in the event the primary distal lumen becomes obstructed during the use of the laryngeal mask. Airflow through the auxiliary ventilation lumen prevents the formation of a pressure gradient between the ventilation tube and the front recess, thereby preventing any obstructing material from becoming lodged within the distal lumen.
Secured to the elongated distal portion of the flexible ventilation tube by an air-tight seal, the inflatable positioning shield serves to secure the laryngeal mask within a patient""s oropharynx, adjacent the tracheal opening. The inflatable positioning shield is composed of an inflatable annular toroid, a recessed front cavity, and several semi-rigid structures molded to fit the anatomy of the laryngeal region. During insertion of the laryngeal mask, the inflatable annular toroid is deflated, reducing the overall size of the laryngeal mask and facilitating proper insertion. Upon positioning adjacent the laryngeal opening, the annular toroid is inflated by means of an externally connected air passage, conforming to the actual and potential space surrounding the rear and peripheral portions of the ventilation tube distal lumen. The inflated annular toroid exerts pressure against the structures of the oropharynx, forming a tightly sealed recessed front cavity surrounding the elongated elliptical distal lumen and the laryngeal opening. A pair of raised longitudinal ridges on the rear surface of the inflatable positioning shield and a frontal notch conforming to the tracheal anatomy further serve to aid in maintaining proper positioning of the laryngeal mask after inflation by preventing lateral movement within the oropharynx cavity. The ridges also facilitate placement by reducing drag.
Upon proper inflation, endo-tracheal tubes and related medical devices passing through the flexible ventilation tube exit the elongated distal lumen axially aligned for entry into the laryngeal opening. Removal of the laryngeal mask from the oropharynx may be accomplished without dislodging any inserted endo-tracheal tubes or related medical devices with the aid of an endo-tracheal tube retaining device. The retaining device, composed of a narrow semi-rigid rod with a softer and pliable cap at one end and a tapered connection adapter at the other, is inserted through the laryngeal mask into the proximal end of an endo-tracheal tube until the tapered connection adapter is securely fitted within the tube. As the laryngeal mask is withdrawn from the patient""s oropharynx, the endo-tracheal tube retaining device maintains the proper positioning of the endo-tracheal tube by allowing a restraining force to be exerted counter to the friction force associated with the withdrawal of the laryngeal mask. Once clear of the oral cavity, the laryngeal mask is slipped off the proximal end of the endo-tracheal tube retaining device, allowing the endo-tracheal tube or related medical instrument to remain properly positioned within the larynx. Finally, the semi-rigid rod of the endo-tracheal tube retaining device can also be used as an intubating stylet for any further medical devices which need to be passed through the oropharynx and into the inserted endo-tracheal tube after removal of the laryngeal mask. Of course the rod can also be used separately as an intubating stylet for direct visualization.
These and other objects and advantages of the present invention will become more apparent from the description that follows.